You want to knock off the high points (some diamonds can sit higher) sharpen a Knife, axe or just use the round metal shank of a screwdiver to mellow it a bit...

The Nanniwa SS tend to swell a bit when they first get wet so let them settle before you start lapping for flatness doing grids,, keep them wet under the tap as you lap them in..

Do two or three good grids and then stop,, They can have you chasing flatness and wasting hone if you don't let them settle...